/Engine/Source/Runtime/Engine/Classes/GameFramework/GameModeBase.h
Return the 'best' player start for this player to spawn from Default implementation looks for a random unoccupied spotAActorchosen as player start (usually a PlayerStart)
[AActor](API\Runtime\Engine\GameFramework\AActor) * ChoosePlayerStart ( [AController](API\Runtime\Engine\GameFramework\AController) * Player )